Detector



v w. L. CARLSON Re. 20,700

April 19, 193s.

TELEVISION SYSTEM original Filed Dc. 2e. 1951 s sheets-sheet 1 Y Bk,

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. S, 38am,

INVENTOR. i@ NDELL L. CARLSON A RNEY.

19., 1938. w, L CARLSQN Re. 20,700

TELEVIS ION SYSTEM original Filed Dec. 2e, 1931 s sheets-sheet 2 y f- E 'Aub 0 10 I@ 4 AMR DETEcTDR AM; .57) /28 L13 C20 43 2f DETEC- VERTICAL TOR SCANNING 3 L25 L30 l' E9 c l 4 /9 DETEcTDR Ik@ DETECTOR Agg? I I 46 D f7 *f8 DETECTOR vf- DETEcTDR ggfffggl fa l L H23 L l 49 5f 2a fifi,- Dsc/LLATDR E 2.9 HJ 47 I F 52 r P/cTuRE DETECTOR A'M), DETECTUR s/sNALs DETEcToR XJ., DETECTOR 2 svcEARJllvL/.frl

wENDEL L. cARLsDN ATTORNEY.

April 19, 1938. w. L. CARLSON TELEVISION SYSTEM Driginal Filed Dec. 26,"1931 I 5 Sheets-Sheet 3 #S915 E22 1a. 432.53;

INVENTOR. WENDELL L.A CARLSO ATTORNEY.

Ann..

Ressued Apr. 19, 1938,

UNITED :STATES l.PMI-:NT OFFICE TELEVISION SYSTEM Wendell L. Carlson, Haddonileld, N. 1. assigner to Radio Corporation of America, a corporation of 'Delaware Original No. 1,975,056, dated September 25, 1934, l vSerial No. 583,193, December 26, 1931. Application for reissue September 10, 193B, Serial 14 Claims. (Cl. 17d-5.a)

My invention relates to improvements in television systems and, more particularly, to systems wherein two or more carrier frequencies are utiand sound modulations on adjacent carrier fre-l quencies, and wherein the tuning for both picture and sound is accomplished by manipulation of a single knob or' other single control element.

Another Aobject of my invention is to provide an improved television system of the character referred to which effectively receives simultaneously and separates two or more modulated carrier waves on adjacent fequencychannels with out permitting any detrimental interference of either wave with the other,

Another object of my invention is to provide an improved system of the characterreferred to which allows for more advantageous utilization of the available frequency band than has been lpossible in such systems proposed heretofore.

Other objects and advantages will hereinafter appear. f

In accordance with my invention, a radiofrequency amplifier is tuned broadly to two carrier frequencies located on adjacent portions of the frequency band, one carrier being modulated by picture signals, the other carrier being modulated by sound signals. The picture and sound frequencies are separated, after heterodyning to produce intermediate frequencies, through two parallel, tuned, intermediate-frequency amplifiers which have the same band widths and the same frequency separation as the modulated sight and sound frequencies.

Further, in accordance with my invention, a system of the character referred to is provided which embodies common radio-frequency and heterodyne oscillator circuits for the sound, picture and synchronizing signals, and separate intermediate-frequency and audio-frequency circuits for said signals, respectively.

My invention resides in a system and method of operation of the character hereinafter described and claimed. l l

For the purpose of illustrating my invention, several embodiments thereof vare shownin the drawings, wherein:

Figure 1 is a diagrammatic view of a television receiving system constructed and operated in accordance withlmy invention;

Figs. 2, 3 and 4 are block diagrams, showing several modifications; and

Figs. 5, 6 and '7 are graphical showings, illus` trativ'e of the principle of operation.

Fig. 8 illustrates a dual channel automatic volume control arrangement.

' In one embodiment of my invention a radiofrequency ampliiier is tuned broadly to two carrier frequencies, one modulated by picture signals, horizontal synchronizing and vertical synchronizing signals, the other modulated by sound signals. Heterodyne detectors, having a common `oscillator, operate toconvert the amplified radio fre.

quencies to different intermediate frequencies which pass through separate channels provided by two parallel, tuned, intermediate-frequency amplifiers. The intermediate amplifiers have the same band widths and the same frequency separation as the modulated pictureand sound frequencies, and are tuned, respectively, to these frequencies.

More specifically, and with reference to Fig. 1, the transmitted carriers, modulated as. stated above, are intercepted by an antenna system I and are amplified by a radio-frequency. amplier ii tuned broadly to both carriers.

For the purpose of separating the various frey quencies so that the same can serve their respective, individual functions, heterodyne detectors I2 and I3, having a common oscillator I4, are employed to convert the amplified radio frequencies to different intermediate frequencies which traverse the channels A and B, respectively.

The channel A comprises a plurality of ampliiier stages I5 and I6 tuned to the intermediate frequency of the carrier modulated by the sound signals and having sufficient selectivity to prevent the picture carrier or'modulation from interfering with the sound reproduction. These signals are detected by a/suitable detector i1, and are supplied through an audio amplier I8 to a loudspeaker I9.

-The channel B comprises a plurality. of intermediate-frequency amplifier stages 2|), 2i and 22 tuned .to pass frequencies which cover the band required for the modulation produced by the picture and synchronizing frequencies, and have sumcient selectivity to prevent the sound carrier or modulation from interfering with the picture reproduction.

The channel B branches out, from individual detectors 23, 24 and 25, into separate channels for the horizontal synchronizing modulation signals. thev ypicture modulation signals, and the vertical synchronizing modulation signals, re-I spectively.

For the purpose of reproducing a picture in accordance with the received picture signals, the latter are supplied, through a suitable circuit 28, to the control grid of a cathode ray tube 26 of usual construction.

'I'he tube 26 is provided at the large end thereof with a fluorescent screen 21. The ray of 'electrons 21a is caused to scan the screen 21 by passing a saw-tooth current wave, from a suitable circuit 28, through electromagnetic coils 3l, and by passing a. saw-tooth current wave, from a suitable circuit 38, through electromagnetic coils 3Ia. l y

The circuits 28, 28 and 38 may be of the same character as those disclosed ln detail in the copending application by Arthur W. Vance. illed June 17, 1931, bearing Serial No. 544,959, and assigned to the RCA Victorl Company, Inc.

In receiving systems embodying other types of picture-reproducing devices than a cathode ray tube, such, for example, as a neon tube and an associated Nipkow disk driven by an electric motor, the impulses from the circuit 28 may 'be utilized to maintain the speed of the motor in synchronism with the corresponding motion or action at the transmitting station, and lthe impulses from the circuit 38 may be utilized to hold the reproduced picture in frame. The terms ,horizontal synchronizing and vertical synchronizing, as used for convenience in the specication and claims, are, therefore, intended to have a broad signicance, and to refer to systems wherein the synchronizing impulses are used to control operating action of other types of picture-reproducing devices such as those of the mechanical variety.

The detector 24 passes all signals to the circuit 28, but the detectors 23 and 25 are preferably so biased beyond cut-off that only the peak modulations, consisting mainly of synchronizing'im'- pulses, will be emciently passed on to the circuits 28 'and 38. This action, whereby the picture and the two kinds of synchronizing impulses are distinguished at the various input circuits for the tube 26, is explained more fully in the copending application referred to.

Individual means, in the form of adjustable resistors 32, 33 and 34, are provided for independently 'varying the respective levels of the horizontal synchronizing signals supplied to the circuit 28, the picture signals supplied to the circuit 29, and the vertical synchronizing signals supplied to the circuit 38.

For the purpose of making the receiving system responsive selectively to a plurality of combinations of modulated carrier frequencies from as many diiferent transmitting stations, each of the latter operating to transmit sound as Well as picture signals, the variable'condensers 35, 36 and 31 of the tuned circuits shown are actuated by a single knob or other suitable, single control element 38, as indicated. 'Ihe receiving system, therefore, is tunable simultaneously for sound and picture signals from anyone of a plurality of transmitting stations, by manual manipulation of the single knob 38.

In the various receiving systems of' this general I character proposed heretofore, difculty has been encountered in adjusting the level of one kind of signals -without eecting an undesirable variation in the level of one or more of the other kinds of signals. Subsequent readjustment of the -latjustment has operated to affect the previous adjustment referred to. It has, therefore, been necessary in the prior art systems to skillfully adjust and readjust the individual control parts, corresponding to the adjustable resistors 32, 33 and 34 in Fig. l, to obtain the best action at the receiver for different conditions of signal levels. Furthermore, adjustment of the radio-frequency circuits, in the prior art systems, to different carrier frequencies from as many different transmitting stations, has entailed a rather laborious readjustment of the control corresponding to the adjustable resistors 32, 33 and 34 in Fig. l.

I propose to avoid the diiiiculties referred to by employing means for automatically maintaining substantially constant the level of the picture signals applied to the detector 24, the level of Ament of my invention, such automatic means embodies a detector tube 38 having its grid circuit supplied with signals from the output end of the intermediate-frequency amplifier in the channel B, through the connections 48 and 4I. The plate circuit of the tube 38 is connected, as shown, to the grid circuits of the amplier stages 28 and 2l. In operation, when the knob 38 is adjusted to tune in a different transmitting sta.- tion, which, for example, increases the levels of the various signals, the tube 38 will draw more plate current and effect a corresponding increase in the negative direction, of the grid bias on the stages 28 and 2l. This compensating action operates, therefore, to maintain the levels of the various signals substantially constant to the grid circuits of the detectors 23, 24 and 26. If a transmitting station is tuned in to cause a decrease in the levels of the various signals, the tube 38 operates in the opposite sense, as will be well understood, to decrease the negative bias on the grid circuits of the stages 28 and 2|, with the result, as before, that the levels in the grid circuits of the detectors 23, 24 and 26 remain substantially constant.

Itis contemplated, in some cases, to provide an automatic volume control for the sound signals in the channel A. For such purpose, the same tube 38 may be used in the same way as is shown in connection with the picture channel B, that is, the plate circuit of the tube 38 would` be connected to the grid circuits of the tubes I5 and I6 in the same way as the connection is made to the vtubes 28 and 2|. When the automatic volume control is incorporated, as explained, in the v sound channel A, it is proposed to remove the manual control I5a from the input circuit of the tube I5 and replace the same with a manual con- B. Such an arrangement is illustrated in Fig. 8. l

The ampliiier tube I`I in Fig. 1 may be omitted in some cases, and the circuit 36 then coupled directly to the circuit 36 in any suitable way. As another alternative, separate and individual radio-frequency circuits for the sound and television carriers may be employed in lieu of the common circuits shown comprising the tube II and the circuits 36 and 36.

For the purpose' of providing further assurance the frequency dierence between the sound and picture carriers.

'I'he seriestuned traps 20d and 23a. may take the form of parallel resonant circuits. Any desired number of thesecircuits mayibe employed and connected to the'ampliiiers in any conventional manner. Traps f-isimilar to 20a may Ialso be tuned so as to reject other frequencies such as a sound-modulated carrier from an adjacent channel station.

The system in Fig. 1 may be modified as shown in Fig. 2, wherein the double heterodyne principle is used. In this modification, the additional heterodyne detectors 42 and 4I, having a corn-k mon oscillator 44, are interposedin the'channels A and B between stages of the intermediate-frequency amplifiers to convert the signals to new frequencies a second time. The connections and operating action, otherwise, are the same as in Fig. 1,and the various parts and circuits have been designated by the lsaine reference numerals which designate corresponding parts and. circuits in Fig. 1.

In Figs. 1 and 2 it has been assumed that the signals have been transmitted in the form of two carrier frequencies, one modulated by/the sound signals and the other modulated by the picture and synchronizing signals. However, if conditions are such that a separate carrier frequency is used for transmitting each kind of signal, the system in Fig. 1 takes the arrangement shown in Fig. 3, wherein the radio-frequency amplifier il, as in Figs. 1 and 2, is tunable broadly to the carrier frequencies from any one of Ia number of transmitting stations. 'I'hese frequencies are converted to intermediate frequencies by heterodyne detectors 45, 46, 41 and 48 having a common oscillator 49. These detectors providel separate channels C, D, E and F for the respective signals. In these channels, the intermediate-frequency amplifiers 50, i, 52 and 53 are tuned, respectively. to the frequencies of the sound signals, the horizontal synchronizing signals, the picture signals, and the vertical synchronizing signals. In Fig. 3, therefore, the various kinds of signals are separated into individual channels for each, from the output side of the radio-frequency ampliiler Il. In Fig. 3, as in Fig. 2, the various parts and circuits have been designated by the same reference numerals which designate corresponding parts and circuits in Fig. 1.

In Figs. 1, 2 and 3 separation of the sound and television channels starts from the first detectors,-

and in Figs. 1 and 2 the picture and the horizontal and vertical synchronizing signals are separated from the second detectors 23, 24 and 25 into their respective channels. In the modification shown in Fig. 4, separation of the sound and television channels starts from a first lntermediate-frequency stage 54, whileseparation of ,the picture and the horizontal and vertical synchronizing signals into their respective channels starts from an audio amplifier 55 supplied from and disposed beyond the second detector 56. A single heterodyne detector 51 is interposed, asl shown, between the radio-frequency amplier Ill and the intermediate-frequency stage 54. l,In this figure, the various parts and circuits have been designated by the same reference numerals spectively.

which designate corresponding parts and circuits in Fig. 1.

In Figs. 2,3 and 4,as in Fig. 1, a'single knob may be empioyedffor simultaneously tuning the system for soundiand picture signals.

In carrying out'v the operation of my improved system, the frequency of the picture 'carrier may be 50,000 kilocycles and that of the sound car` xier may be 51,000 kilocycles. This condition is represented graphically in Fig. 5. In this case, thev picture transmitter `nay'be modulated up to 500kilocycles and the sound transmitter may be modulated up to kilocycles. as indicated. 'I'his provides a guard band of 490 kilocycles between the sound and picture modulation frel quencies, the total frequency b and requiredvfor one station being 1510 kilocycles. This band of frequencies is impressed on the radio frequency I input circuit of the receiver. which may have a characteristic similar to the curve 5B in Fig. 7.'

The local heterodyne oscillator may be operating at 45,000 kilocycles which will beat with the received signals to give a picture intermediate frequency of 5000 kilocycles plus and minus 500 kilocycles and a sound intermediate frequency of 6000 kilocycles plus and minus 10 kilocycles. These signals are,in turn, impressed on the intermediate-frequency channels `or circuits A and B in Fig. 1, for example, which may have characteristics as shown by the curves 59 and 60, re-

It is important that the attenuation ofthe picture intermediate-frequency amplifier at 6000 kilocycles be sumcient to prevent the sound carrier from interfering with the picture reproduction. The desired attenuation is. obtained by employing a number of resonant transformers such as I3a and rejector circuits such as the traps a and 23a in Fig. 1..

The same receiver maybe employed for receiving a single side band with carrier-picture transmission. In this case, the frequency of the From the foregoing,'it willbe seen that I have provided an improved television receiving system which can be easily adjusted for different operating conditions, which can simultaneously receive two or more signals in duplex without cross interference) which can be tuned to different transmitting stations by turning a single knob, and which automatically adjusts itself to compensate for varying conditions of levels of the intercepted signals.

Furthermore, it will be understood from the foregoing description that by reason 'of the cooperative action between the various mechanical and electrical parts of my improved television receiving system,` considered as a whole, I have provided a system which embodies an automatic volume control device in connection with the plcture-signal amplifier channel and which can also synchronizing signals.

ing circuits 2l and Ill. For this reason the scanning action of the cathode ray tube 26 might fall out of synchronism with such action at the transmitter. Also, the overall brilliancy of the reproduced picture might decrease substantially, and even to a point whereat the picture would not be recognizable. on the other hand, if me lvei cf the picture and synchronizing signals should increase substantially due to tuning from a distant station to a. local station, for example, the amplifier might be overloaded and, also, the overall brilliancy of the picture on the screen 21 might increase to an undesirable extent. While the automatic volume control associated with the channel B avoids these difllculties, it would ordinarily require skillful manipulation of the various adjusting knobs such as are necessary in th'e systems proposed heretofore to tune the receiverfor most emcient reception of the picture and synchronizing signals. v

In my improved system, however, the single tuning knob' 38 is mechanically connected to both the radio-frequency amplifier Il and the heterodyne detector I4, and the connections are such thatu when the sound-signal carrier frequency from a particular transmitting station is heterodyned to substantially the middle of the band width of intermediate frequencies to which the sound-signal amplifier channel A is tuned relatively sharply, the picture-signal carrier frequency is then heterodyned to a predetermined frequency within the band width of intermediate frequencies to which the channel Bis tuned relatively broadly. That is, the knob 3B is turned until the sound signals from a particular transmitting station are received well, in which case the entire picture-signal channel will also be tuned for most eilicient reception of the picture and Furthermore, by providing the three detector tubes 23, 25 and 24 at the output end of the channel B, any one of the resistors 32,-34 and 33 associated, respectively, with these tubes can be adjusted without alecting adjustment of the other tubes.

The entire action, therefore, insures very eilicient and positive operation, with the synchronizing signals onthe same carrier with the picture signals, this being important for the reason that the synchronizing signals are then applied with the picture signals to the control grid of the tube 26, and, being negative or in the black direction, are effective to cut off the ray during return deflection thereof in both the horizontal and vertical directions.

While only a few preferred embodiments of my invention have been disclosed, it will be undrstood that other embodiments are feasible without departing from the spirit of my invention or the scope of the claims.

I claim as my invention:

l. In a television receiver, a radio-frequency amplifier tunable to a plurality of pairs ofcarrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing signals at relatively high and relatively low frequencies como and the other carrier being modulated by sound signals, heterodyne detector means including an oscillator and supplied from said amplifier for converting the amplified carrier frequencies to different intermediate carrier frequencies, a picture-signal amplifier channel supplied from said detector means and tuned relatively broadly to a given band widthof intermediate frequencies over a range of at least substantially one thousand kllocycles. a sound-signal amplifier channel supplied from said detector means and tuned relatively sharply to.,a band width of intermediate frequencies over a range of at least substantially ten kilocycles and which is spaced from the liirstmentioned band byan amount representing a frequency band width of at least substantially four hundred kilocyclesl a single manually-operable element for tuning the radio-frequency amplifier to any one of said pairs of carrier frequencies and for simultaneously adjusting said heterodyne detector means to vary the intermediate carrier frequencies in such manner that for reception of any pair of modulated carrier frequencies said picture-signal amplifier channel will be tuned to a predetermined frequency within said first-mentioned band width of intermediate frequencies when the sound-signal intermediatefrequency carrier is tuned to substantially the middle of the second-mentioned band width of intermediate frequencies to which said soundsignal amplifier channel istuned relatively sharply, means associated with said picture-signal ampliiler channel for automatically maintaining the level of the output signals therefrom substantially constant, a sound-reproducing device supplied from said sound-signal amplifier channel, a. cathode ray picture-reproducing device, first and second and third detector tubes supplied from said picture-signal amplifier channel, means supplied only from said first detector tube for deflecting the rayfat the said relatively high frequency, and means supplied only from said second detector tube for deiiecting the ray at the said relatively low frequency, said cathode ray device being supplied with picture signals from only said third detectortube.

2. In a television receiver, a radio-frequency amplifier tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing signals at relatively high and relatively low frequencies and the other carrier being modulated by sound signals,i heterodyne detector means including an oscillator and supplied from said amplifier for converting the amplled carrier frequencies to different intermediate carrier frequencies, a picture-signal ampllner channel supplied from said detector means and t'uned relatively broadly to a given band width of intermediate frequencies over a range of at least substantially one thousand kilocycles, a sound-signal amplifier channel supplied from said detector means and tuned relatively sharply to a band width of intermediate frequencies over a range of at least substantially ten kllocycles and which is spaced from the firstmentioned band by an amount representing a lfrequency band width of at least substantially nais at relatively high and relatively low fre-l will be tuned to a predetermined frequency within said first-mentioned band width ofintermediate frequencies when the'sound-signal intermediatefrequency carrier is tuned to-substantially the middle of the second-mentioned band width of intermediate frequencies to which said sound-signal amplifier channel is tuned relatively sharply, means associated with said picture-signal amplifier channel for automatically maintaining the level of the output signals therefrom substantially constant, a sound-reproducing device supplied from said sound-signal amplifier channel, a picture-reproducing device supplied with picture signais from said picture-signal amplifier, and means supplied with synchronizing signals from said picture-signal amplifier for effecting scanning action of said picture-reproducing device at,

a rate corresponding to the frequency of occurrence of the synchronizing signals.

3. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing sigquencies, and the other carrier being modulated by sound signals, heterodyne detector means including an oscillator, said detector means being supplied with signals from said selector for converting the selected carrier frequencies to different intermediate carrier frequencies, a picture signal amplifier channel supplied from said detector means and tuned relatively broadly to a given band width of intermediate frequencies over a range of at least onev thousand kilocycles, a sound'signal amplifier channel supplied from. said detector meansand tuned relatively sharply to a band width of intermediate frequencies over l a range of at least five kilocycles and which is spaced from the first-mentioned band by an amount representing a frequency band Width of at least two hundred kilocycles, a, single manually operable element for tuning the radio frequency selector to any one of said pairs of carrier frequencies and for simultaneously adjusting the heterodyne detector means to vary the intermediate carrier frequencies in such manner that for reception of any pair of modulated carrier frequencies said picture signal will be tuned to a predetermined frequency within the operating frequency range of said first-mentioned band of intermediate frequencies when the sound signal intermediate frequency carrier is tuned to a predetermined frequency Within the operating frequency range of the second-mentioned band of intermediate frequencies, a. sound reproducing device supplied from said sound signal amplifier channel, a picture reproducing device supplied with picture signals from said picture signal amplifier, and meansl supplied with synchronizing signals from said picture signal amplifier for effecting scanning actionof said picture reproducing device at a rate corresponding to the frequency of occurrence of the synchronizing signals.

4. In a television receiver, a radio frequency selector tunable to a plurality of pairsof carrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing signals at relatively high and relatively low frequencies, and the other carrierbeing modulated by sound signals, heterodyne detector'means including an oscillator, said detector v'means 'being supplied with signals from said selector for converting the selected carrier frequencies to different intermediate carrieryfrequencies, a picture signal amplifier channel supplied from said detector means and tunedrelativel'y broadly to a` given band width of intermediate frequencies over a range of at least one thousand kilocycles, a sound signal amplifier channel supplied from said detector meansv and tuned to a band width of intermediate frequencies over a` range of at least 2% of the band width of the picture signal amplifier and which is spaced from the first-mentioned band by an amount representing a frequency band width of at least four hundred kilocycles, a single manually operable element for tuning the radio frequency selector to any one of said pairs of carrier frequencies and for simultaneously adjusting the heterodyne detector means to vary 'the intermediate carrier frequencies in such manner that for reception of any pair of modulated carrier frequencies said picture signal will be tuned to a predetermined frequency within said first-mentioned band width of intermediate frequencies when the sound signal intermediate frequency carrier is tuned to a predetermined frequency within the second-mentioned band of intermediate frequencies, a sound reproducing device supplied from said sound signal amplifier channel, a picture reproducing device supplied with picture signals from said picture signal amplier, and means supplied with synchronizing signals from said picture signal amplifier for eecting scanning action of said picture reproducing device at a rate corresponding to the frequency of occurrence of the synchronizing signals.

5. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing signals at relatively high and relatively low frequencies, and the other carrier being modulated by sound signals, heterodyne detector means including an oscillator, said detector means being supplied with signals from said selector for converting the selected carrier frequencies to different intermediate carrier frequencies, a picture signal amplifier channel supplied from said detector means and tuned relatively broadly to a given band width of intermediate frequencies over a range of at least one thousand kilocycles, a sound signal amplifier channel supplied from said detector means and tuned to a band width of intermediate frequencies over a range of the order of at least ten kilocycles and which is spaced from the first-mentioned band by an amount representing a frequency band width of at least four hundred kilocycles, a single manually operable element for tuning the radio frequency selector to any one of said pairs of carrier frequencies and for simultaneously adjusting the heterodyne detector means to vary the intermediate carrier frequencies in such manner that for reception of any pair of modulated carrier frequencies said picture signal will be tuned to a predetermined frequency within said first-mentioned band width of intermediate frequencies when the sound signal intermediate frequency carrier is' 6. In a television receiver, a radio frequency selector tunable to 'a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by picture signals and synchronizing signals at relatively high and relatively low frequencies, and the other carrier being modulated by sound signals| heterodyne detector means including an oscillator, said detector means being supplied with signals from said selector for converting the selected carrier frequencies to different intermediate carrier frequencies, a picture signal amplifier channel supplied from said detector means and tuned relatively broadly to a given band width of intermediate frequencies over a range of at least one thousand kilocycles, a sound signal amplifier channel supplied from said detector means and tuned to a band width of intermediate frequencies over a range of the order of at least 2% of the band width of the picture signal amplifier and which is spaced from the first-mentioned band by an amount representing a frequency band width in the order of four hundred kilocycles, a single manually operable element for tuning the radio frequency selector to any one oi' said pairs of carrier frequencies and forfsimultaneously adjusting the heterodyne detector means to vary the intermediate carrier frequencies in such manner that for reception of any pair of modulated carrier frequencies said picture signal will be tuned to a predetermined frequency Within said first-mentioned band Width of intermediate frequencies when the sound signal intermediate frequency carrier is tuned to a predetermined frequency within the second-mentioned band of intermediate frequencies, a sound reproducing device supplied from said sound signal' amplifier channel, la picture reproducing device supplied with picture signals from said picture signal amplifier, and means supplied with synchronizing signals from said picture signal amplifler for effecting scanning action of said picture reproducing device at a rate corresponding to the frequency of occurrence of the syn-l chronizing signals.

7. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by picture signals and .synchronizing signals at relatively high and relatively low frequencies, and the other carrier being modulated by sound signals, heterodyne detector means including an oscillator, said detector means being supplied with signals from said selector for converting the selected carrier frequencies to different intermediate carrier frequencies, a picture signal amplierchannel supplied from said detector means and tuned relatively broadly to a given band width of intermediate frequencies over a range of at least one thousand kilocycles, a sound signal amplifier channel supplied from said detector means and tuned to a band width of intermediate frequencies over a range of at .frequency within said first-mentioned band width 10i intermediate frequencies when the sound sigl nal intermediate frequency carrier is tuned to a predetermined frequency within the secondmentioned band of intermediate frequencies, means associated with said picture signal arnplliler channel for automatically maintaining a level of the output signals therefrom substantially constant, a sound reproducing device supplied from said sound signal amplifier channel, a picture reproducing device supplied with picture signals from said picture signal amplifier, and means supplied with synchronizing signals from said picture signal amplifier for effecting scan-, ning action of said picture reproducing device at a rate corresponding to the frequency of occurrence of the synchronizing signals.

8. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one of said separate carriers being modulated by video signals and the other of said carriers being modulated by audio signals, means for detecting each of said carrier frequencies, means for developing a potential representative of the signal level of one of said carriers, and means for controlling the level of the signals of both the sound and video signals with said developed potential.

9. In a television receiver, a radio frequency selector tunable to a, plurality of pairs of carrier frequencies, one of said separate carriers being modulated by video and synchronizing signals and the other of said carriers being modulated by audio signals, means for detecting each of said carrier frequencies, means for developing a potential representative of the signal level of one of said carriers, and means for controlling the level of the signals of both the sound and video' signals with said developed potential.

10. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one of sai-d separate carriers being modulated by video signals and the other of said carriers being modulated by audio signals, a common means for detecting each of said frequencies in a pair of said carrier frequencies, means for developing from one oi' said signals a potential representative of the received signal intensity, and means for controlling the level of both sound and video signals with such developed potential. l

11. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one of said separate carriers being modulated by video and synchronizing signals and the other of said carriers being modulated by audio signals, a 'common means for detecting each of said frequencies in a pair of said carrier frequencies, means for developing from one of said signals a potential representative of the received signal intensity, and means for controlling the level of both sound and video signals with such developed potential.

l2. In a television receiver, a radio freq'uency selector tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by video signals and the other carrier oi',l each pair being modulated by sound signals, means for detecting such carriers so as to develop signals representative of the video and audio signal values, means for carrying each frequency of said pairs of carrier frequencies along separale channels, means for developing from the video signals a direct potential, and means for controlling the gain of each of said channels in accordance with said direct potential.

` 13. In a television receiver, a radio frequency selector tunable to a plurality of pairs of carrier frequencies, one carrier of each pair being modulated by video and synchronizing signals and the other carrier of each pair being modulated by sound signals, means for detecting such carriers so as to ldevelop signals representative of the video and audiov signal values, means for carrying each frequency lof said pairs of carrier frequencies along separate channels, means for developing from the video signals a direct potential, and means for controlling the gain of each of said channels in laccordance with said direct potential.

14. In a television receiver, a radio frequency riers so as to develop signals representative oi.

the video and audio signal values, means for carrying each frequency of said pairs of carrier ire- `quencies along separate channels, means for developing from the video'signals a direct potential, and means for controlling the gain of each o! said channels in accordance with said direct potential. l

WENDELL L. CARLSON. 

